In a paper mill a continuous strip of paper moving longitudinally at high speed must be transversely cut into individual sheets that must then be piled in individual stacks on pallets or the like. The stacking must be done without interrupting the flow of continuously arriving sheets, so that when a stack is complete it is necessary to get it out of the way and bring a new pallet into place while somehow catching and holding the sheets that arrive during the changeover.
Accordingly U.S. Pat. No. 4,949,953 of E. Claassen describes an arrangement where the pallet is carried on a vertically displaceable main platform, and where a horizontally displaceable auxiliary platform can be moved into position above the main platform to catch the arriving sheets as the full pallet on the main platform is switched for an empty one. L-shaped clamping elements hold the partial stack on the auxiliary platform in place after the empty pallet is raised into position below it so the auxiliary platform can be withdrawn to deposit the stack it carries on the empty pallet, whereupon stacking can proceed as beforehand.
Other similar solutions are described in German 3,535,113 of J. Bodewein (U,.S. equivalent U.S. Pat. No. 4,799,847), 3,616,470 of N. Martini, and 3,723,113 of H. Hohenschutz. All are quite complicated, entailing substantial complex structure, so that they cannot be counted on to perform satisfactorily in the long run.